Construction of oxygen-vacancy abundant Co₃O₄ nanorods for high-performance solid-state supercapacitor

Designing and optimizing electrode materials for supercapacitors (SCs) is generally considered to be an effective way to enhance their electrochemical performance. It is an attractive approach to obtaining high capacity electrodes by engineering the nanostructure and oxygen vacancies of electrodes. Herein, we developed an efficient and green strategy to facilitate one-dimensional (1D) Co₃O₄ nanorods with abundant oxygen vacancies via Co nanorods oxidation by H₂O₂ treatment, significantly promoting the electrochemical energy storage. The unique Co₃O₄ NRs due to 1D nanostructure and oxygen vacancy, exhibit a high specific capacity of 627.4 mF cm⁻² at a current density of 0.5 mA cm⁻² and excellent rate capacity (57.8% capacitance retention at 10 mA cm⁻²). Furthermore, an asymmetric supercapacitor (ASC) constructed with the Co₃O₄ nanorods as electrode materials shows a high energy density of 0.187 mWh cm⁻² at a power density of 1.261 mW cm⁻². This nanostructure and vacancy engineering strategy put forward in this work is an inspiring example for the design of the next generation of SCs.